Assume a patient lies on bed to receive 1V infusion. There are two types of infusion systems. One is by pump, another is by gravity. The pump infusion system is very costly and often encounters maintenance trouble. Therefore, many hospital workers prefer to use the traditional gravity infusion system. The gravity IV infusion line consists of three parts: (a) An IV bottle contains medical liquid and air above the medical liquid; (b) Infusion line includes a liquid needle inserted inside the IV bottle to receive medical liquid, a plastic liquid tube with one end connected to the liquid needle as liquid inlet and another end connected to the IV injection needle for injecting the medical liquid into the patient vein. A drop chamber is connected in the middle of the liquid tube for observing the liquid flow rate. A switch is connected also in the middle of the liquid tube to control the flow rate manually; (c) Air line includes an air needle inserted into the IV bottle to apply air pressure for driving the liquid flow, and a plastic air tube with one end connected to the air needle as air outlet and another end opened to the environment as air inlet. It is noted that some hospitals have removed the air line for the above setup if the IV bottle is made of flexible plastic bag. As the medical liquid in the IV bottle drops to an empty state, that is, the IV bottle is almost empty, the IV bottle must be replaced by a new one, otherwise air may enter the infusion line and causes serious medical problems.
So far, the job of bottle replacement needs frequent supervision from patient and nurses by eyeball. This task becomes a heavy burden of medical workers, particularly at night. To develop an alarming system at the empty state for IV infusion becomes a big demand from hospitals and patients. The accurate determination of the empty state becomes very important, if it is determined being too high or too early, a lot of medical liquid may be wasted, if it is determined being too low or too later, the medical liquid in the IV bottle may be completely drained before a nurse replaces a new IV bottle and therefore a medical accident may occur. In addition, the weight of the medical liquid in an IV bottle may vary widely because its different specific density and additive medicines. Also, the weight of an empty IV bottle varies widely because of it different material, size and manufacturer etc. Therefore, estimate of the empty state by using flow rate integration or by estimating the weight of an empty IV bottle may generate a big error.
Furthermore, the hospitals also wish to monitor whole IV infusion process for better care of the patients. For example, an IV infusion process may go wrong if a patient or particularly a baby moves violently during infusion. In this case, monitoring whole infusion process, e.g., the liquid level and the infusion speed at each time moment, becomes necessary. Unfortunately, there is no any satisfied device existing in the current market for this task.
The present invention provides a method for accurately determining the empty state of an IV bottle in an IV infusion monitoring device or in a network monitoring system, which not only gives alarm when the IV bottle needs replacement, but also provides all infusion data during whole infusion process, e.g., the liquid level (remaining liquid weight), the liquid flow rate (infusion rate) and the remaining time from the completion of the infusion process as well as the empty state. The present invention also includes a communication network, so that the nurses or other hospital workers can monitor the whole IV infusion process of each patient from either a close or a remote location through the network.
U.S. Pat. No. 3,656,478 to Swersey, discloses an infusion monitor which is able to supply a medical liquid to a patient at either a high rate or low rate, depending upon the weight of the patient. If the weight of the patient decreases below a preset value, the infusion monitor is switched to the high speed. If the weight of the patient returns to normal, the infusion monitor switches back to the low speed. The present invention is apparently different from the Swersey's. The present invention provides a method for determining the empty state in an IV infusion monitoring device, which can measures and monitors the weight of the medical liquid in the IV bottle, and calculates the liquid flow rate during infusion.
U.S. Pat. No. 3,939,360 to Jackson discloses a liquid level sensor and electrode assembly therefore. Jackson's disclosure applies three capacitance plates to measure the capacitance which is related to the liquid level. The present invention is related to an IV infusion monitoring device, which applies weight measurement of the medical liquid in the IV bottle by an electric load sensor to monitor the infusion process.
U.S. Pat. No. 4,589,372 to Smith discloses a dispensing system similar to the Swersey's. The Smith's system first determines the weight of an animal subject, and then a delivery unit supplies a predetermined amount of material to the animal subject. The amount of supplied material is a function of the weight of the subject. It is apparent that the present invention is completely different from the Smith's. The present invention is related to a device, which monitors the weight of the remaining medical liquid in the IV bottle and the liquid flow rate during infusion, not the control of the infusion speed as a function of the weight of the animal subject.
U.S. Pat. No. 4,670,007 to Wheeldon et al. discloses an infusion monitoring system by measuring the weight loss of the fluid container. Wheeldon's invention is for controlling the infusion rate of a pump-based infusion system, in which the infusion rate is controlled by the pump. Although Wheeldon includes an empty state indicator, it does not disclose any method to set up the empty state. However, the present invention discloses methods for accurately determining the empty state in an infusion monitoring device used to monitor all infusion data including weight, flow rate and time etc.
U.S. Pat. No. 5,563,584 to Rader et al. discloses a liquid level sensing and monitoring system for medical fluid infusion systems. Rader's disclosure applies pressure sensor technology. A pressure sensor is inserted into the outlet of a liquid container and contacts the liquid for detecting the liquid level. The present invention is related to a monitoring device, which applies the load sensor for measuring the weight of the medical liquid in the IV bottle during infusion.
US Pat. Application No. US2005/0137653A1 to Friedman discloses a very general monitoring system for monitoring a plurality of medical devices including infusion pump. However, it does not disclose any communication system to have remote and mobile monitoring function. Furthermore, it does not disclose specifically any method for determining the empty state of an IV bottle for infusion monitoring purpose.
US Pat. Application No. US2006/0064053A1 to Bollish et al. discloses a monitoring system to monitor and control 2 pump devices at same time. The present invention is related to an infusion monitoring device for monitor a gravity-driven infusion system. Furthermore, Bollish does not disclose any method for determining the empty state of the IV bottle.
The present invention provides a method for determining the empty state of an IV bottle in an TV infusion monitoring device or in a network monitoring system, which is capable for measuring and monitoring the infusion data during whole infusion process, as well as for giving alarm when the gross weight of the IV bottle drops to the empty state. The present invention is apparently different from and superior over all the prior arts in function, structure, cost, accuracy and reliability, as well as ease of use.